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  Systems and methods for hydrogen storage and generationUSPTO Application #: 20070267288Title: Systems and methods for hydrogen storage and generation Abstract: Provided are systems for storing and generating hydrogen comprising a solution that comprises a reaction product of (a) a photosensitized oxidation product of methanol; and (b) a reduction product of oxygen and a photoreduced photosensitizer, wherein the system generates hydrogen gas when a basic material is added to the solution. Preferably, the photosensitizer is an anthraquinone. The photosensitizer may be dissolved in the liquid solution or may be in a solid phase in the solution. Preferably, the solid phase is a porous membrane, most preferably an inorganic oxide xerogel membrane, and the photosensitizer is complexed to an inorganic oxide xerogel material. Also provided are methods for storing hydrogen by providing methanol, an oxidative photosensitizer, oxygen, and light that is absorbed by the photosensitizer. Hydrogen gas is generated by the addition of a basic material. (end of abstract) Agent: Optodot Corporation - Allston, MA, US Inventor: Steven Allen Carlson USPTO Applicaton #: 20070267288 - Class: 20415752 (USPTO) The Patent Description & Claims data below is from USPTO Patent Application 20070267288. Brief Patent Description - Full Patent Description - Patent Application Claims
RELATED APPLICATIONS [0001]This application claims the benefit of U.S. Provisional Patent Application No. 60/802,463, filed May 21, 2006, entitled "Systems and Methods for Hydrogen Storage and Generation," by S. Carlson, which is incorporated herein by reference for all purposes. FIELD OF THE INVENTION [0002]The present invention relates generally to the field of systems and methods for hydrogen storage and generation. More particularly, this invention pertains to methods of storing hydrogen by providing methanol, an oxidative photosensitizer, oxygen, and light that is absorbed by the photosensitizer. Hydrogen gas is generated by the addition of a basic material. The present invention also pertains to systems for storing and generating hydrogen that utilize such methods. BACKGROUND [0003]Throughout this application, various patents are referred to by an identifying citation. The disclosures of the patents referenced in this application are hereby incorporated by reference into the present disclosure to more fully describe the state of the art to which this invention pertains. [0004]Hydrogen gas is highly desirable as a fuel for vehicles and for other energy related applications such as stationary power systems and fuel cells because its combustion product is water and its fuel content in terms of weight is very high. The various fossil fuels, such as oil, natural gas, and coal, produce carbon dioxide as their main combustion product. The environmental impact of increased carbon dioxide in the atmosphere in causing global warming has led to increased efforts to find improved alternative energy sources that do not generate carbon dioxide. Besides hydrogen fuels, these alternative energy sources include photovoltaic cells, wind energy, nuclear energy, and hydroelectric power. [0005]One of the major challenges in utilizing hydrogen as a fuel is the difficulty of storing hydrogen in a safe and economical condition. In order to use hydrogen as a fuel in vehicles, a sufficient amount of hydrogen must be provided to the vehicle. Conventional approaches include liquefying the hydrogen at very low temperatures and storing the hydrogen as a gas under high pressure, such as thousands of pounds per square inch. Liquefication and pressurization require relatively expensive processing and storage equipment and also pose safety concerns in storing and dispensing the liquid hydrogen by these approaches. The energy consumed in liquefying hydrogen gas is about 30% of the energy available from the hydrogen. Storing hydrogen under high pressure in cylinders typically results in only 1 to 4% by weight of hydrogen storage in the heavy steel or other metal cylinders. Other approaches include combining the hydrogen with another material, such as in reversible metal hydrides, at an acceptable weight percent of hydrogen that is safe and is adapted for use as a fuel. Still another approach is to convert water to hydrogen by reacting elemental metals, such as magnesium, with water as, for example, described in U.S. Pat. Nos. 6,018,091, 6,117,206, and 6,322,723, to Thomas. A number of the approaches to store, supply, and generate hydrogen are described in U.S. Pat. Nos. 6,745,801 and 6,886,609, both to Cohen et al. [0006]It would be advantageous if a safe and convenient method of storing and generating hydrogen gas were available for use in a variety of energy related applications such as vehicles and fuel cells. It would be particularly advantageous if this method had the flexibility to store the hydrogen gas in a safe and economical liquid form until it needed to be generated or converted into hydrogen gas or, alternatively, this method could form and generate the hydrogen gas in a single step on demand from a safe and economical liquid solution. SUMMARY OF THE INVENTION [0007]A system for storing and generating hydrogen of the present invention comprises a solution comprising (a) a photosensitized oxidation product of methanol; and (b) a reduction product of oxygen and a photoreduced photosensitizer, wherein the system generates hydrogen gas when a basic material is added to the solution. Another system for storing and generating hydrogen of this invention comprises a solution comprising the reaction product of (a) a photosensitized oxidation product of methanol; and (b) a reduction product of oxygen and a photoreduced photosensitizer, wherein the system generates hydrogen when a basic material is added to the solution. In a preferred embodiment, the reaction product is bis-(hydroxymethyl) peroxide. In one embodiment, the solution comprises water. In one embodiment, the solution comprises methanol. In one embodiment, the photosensitizer is an anthraquinone. In one embodiment, the basic material comprises an inorganic hydroxide, preferably sodium hydroxide or potassium hydroxide or a combination thereof. In one embodiment, the photosensitizer is dissolved in the solution. [0008]In one embodiment of the systems of this invention, the photosensitizer is in a solid phase in the solution. In one embodiment, the solid phase is a porous membrane comprising a xerogel material and at least a portion of the photosensitizer is complexed to the membrane. In one embodiment, the photosensitizer is an anthraquinone with one or more anionic groups and at least one of the anionic groups is complexed to the xerogel material. In one embodiment, the membrane is a xerogel membrane. [0009]In one embodiment of the systems of the present invention, the photosensitized oxidation product is formaldehyde. In one embodiment, the reduction product of oxygen and the photoreduced photosensitizer is hydrogen peroxide. [0010]One method of the present invention for storing hydrogen comprises the steps of (a) providing a solution comprising methanol; (b) providing a photosensitizer for the oxidation of methanol; (c) providing oxygen gas; and (d) providing light that is absorbed by the photosensitizer, wherein the photosensitizer is dissolved in the solution or is in a solid phase in the solution, wherein the photosensitizer absorbs light and oxidizes the methanol and forms a photoreduced photosensitizer, and further wherein the oxygen gas oxidizes the photoreduced photosensitizer to regenerate the photosensitizer and is reduced to form hydrogen peroxide. In one embodiment, the photosensitized oxidation product of methanol is formaldehyde. In one embodiment, the photosensitized oxidation product of methanol and the hydrogen peroxide react to form a reaction product that generates hydrogen in the presence of a basic material. In one embodiment, the reaction product is bis-(hydroxymethyl) peroxide. In one embodiment, the yield of hydrogen from the reaction product in the presence of the basic material is 100% based on the relative molecular weights of hydrogen and the reaction product. [0011]In one embodiment of the methods of this invention, prior to the formation of the reaction product, the solution is placed into a storage container. In one embodiment, the solid phase is removed from the solution in the storage container subsequent to the formation of the reaction product. [0012]In one embodiment of the methods of the present invention, subsequent to the formation of the reaction product, the solution is placed into a storage container. In one embodiment, the solid phase is removed from the solution in the storage container subsequent to the formation of the reaction product and prior to or after placing the solution into the storage container. [0013]In one embodiment of the methods of this invention, the solution comprises water. In one embodiment, the photosensitizer is an anthraquinone. In one embodiment, the basic material comprises an inorganic hydroxide, preferably sodium hydroxide or potassium hydroxide or a combination thereof. In one embodiment, the photosensitizer is dissolved in the solution. [0014]In one embodiment of the methods of the present invention, the photosensitizer is in a solid phase in the solution. In one embodiment, the solid phase is a porous membrane comprising a xerogel material and at least a portion of the photosensitizer is complexed to the membrane. In one embodiment, the photosensitizer is an anthraquinone with one or more anionic groups and at least one of the anionic groups is complexed to the xerogel material. In one embodiment, the membrane is a xerogel membrane. DETAILED DESCRIPTION OF THE INVENTION [0015]The systems and methods of the present invention provide a flexible, safe, and effective approach to storing and generating hydrogen by utilizing a liquid solution that forms precursor products to producing hydrogen and that can generate hydrogen gas immediately upon the formation of the precursor products or, alternatively, can store the precursor products and generate hydrogen gas at a later desired time. [0016]A system for storing and generating hydrogen of the present invention comprises a solution comprising (a) a photosensitized oxidation product of methanol; and (b) a reduction product of oxygen and a photoreduced photosensitizer, wherein the system generates hydrogen gas when a basic material is added to the solution. Another system for storing and generating hydrogen of this invention comprises a solution comprising the reaction product of (a) a photosensitized oxidation product of methanol; and (b) a reduction product of oxygen and a photoreduced photosensitizer, wherein the system generates hydrogen when a basic material is added to the solution. In a preferred embodiment, the reaction product is bis-(hydroxymethyl) peroxide. In one embodiment, the solution comprises water. In one embodiment, the solution comprises methanol. In one embodiment, the photosensitizer is an anthraquinone. In one embodiment, the basic material comprises an inorganic hydroxide, preferably sodium hydroxide or potassium hydroxide or a combination thereof. In one embodiment, the photosensitizer is dissolved in the solution. [0017]The liquid solution of the systems of the present invention comprises a photosensitized oxidation product of methanol. In a preferred embodiment, the photosensitized oxidation product is formaldehyde. The formaldehyde may be present in the liquid solution as a monomer, as a polymer, as part of a reaction product with another material present in the solution such as hydrogen peroxide, or combinations thereof. These chemical states of formaldehyde-related species may be in equilibrium with one or more of the other states and are capable of generating hydrogen gas in combination with the presence of hydrogen peroxide and a basic material, such as sodium hydroxide. [0018]The photosensitized oxidation product of methanol is preferably prepared by oxidizing methanol using a photosensitizer and ultraviolet and/or visible light depending on the wavelengths at which the photosensitizer is effective. Alternatively, the oxidation product of methanol may be made by a non-photolytic oxidation process, such as by a thermal catalytic process. The photosensitized oxidation typically involves a photo-induced abstraction of a hydrogen atom from the methanol that leads to a photoreduced photosensitizer with added hydrogen atoms and to an oxidation product of methanol, typically formaldehyde. [0019]The liquid solution of the systems of this invention also comprises a reduction product of oxygen and a photoreduced photosensitizer. In a preferred embodiment, the reduction product is hydrogen peroxide. By choosing a photosensitizer for oxidizing methanol that becomes reduced by the addition of hydrogen atoms to form a photoreduced photosensitizer and that regenerates the photosensitizer by auto-oxidation with oxygen, a reduction product of oxygen is formed, typically hydrogen peroxide. Since the photosensitizer is regenerated, it acts as a catalyst in producing the oxidation product of methanol and the reduction product of oxygen and is not consumed during the generation of the precursor products for generating hydrogen. Also, if the photosensitizer is present when the hydrogen gas is generated, typically the photosensitizer is unchanged by the chemical reactions that generate the hydrogen gas. Continue reading... Full patent description for Systems and methods for hydrogen storage and generation Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Systems and methods for hydrogen storage and generation patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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